Integrated circuits typically comprise a supply port for power supply, a ground port as well as an input port. Via the input port, the integrated circuit can be supplied with electrical signals to be processed by the integrated circuit.
In order to protect the integrated circuit against electrostatic charge or discharge the supply port, the input port and the ground port are provided with a diode arrangement as for instance illustrated in FIG. 1. The integrated circuit 1 comprising a supply port 2, an input port 4 and a ground port 6 has a first diode 8 and a second diode 9 forming a protective diode arrangement to prevent that electrostatic charge or discharge is present to the rather sensitive input port 4.
However, there may arise situations, in which either the supply port 2 or the ground port 6 is disconnected from a supply voltage V1 or from ground. In this case, e.g. with a disconnected supply port 2 and as illustrated in FIG. 1, a voltage V2 present at the input port 4 may propagate from the input port 4 via the diode 8 to the supply port 2.
In such a situation the power supply for the integrated circuit 1 is provided or branched off from the input signal. If for instance an alternating clock signal is present at the input port 4 the electrostatic discharge (ESD) protection diode 8 may rectify the clock signal and may create and provide a supply voltage for the integrated circuit 1. The integrated circuit may then power up unintentionally.
A corresponding situation may also arise when the ground port 6 is disconnected or broken. In this case, the input port 4 may substitute or replace the ground port 6 and the integrated circuit 1 may be supplied through the diode 9.
Interruption of the supply or of the ground may take place either by accident or when the integrated circuit 1 becomes subject to an attack. In these circumstances, the integrated circuit 1 may be unintentionally operated or activated, which may lead to undesired operation modes of the integrated circuit 1, to a damage of the integrated circuit 1 or of the device making use of the integrated circuit 1.